Taking to her Instagram page, the 21-year-old penned a heartfelt birthday message to her boyfriend and father of her child.

"Watching you evolve into the partner, friend, son, and father you are today has been so fulfilling my real life bestie & hubby all wrapped into one. I love you and I’m so so proud of you. Happy happy birthday," she wrote before saying she wanted the two to make another baby.

This is not the first time Kylie has hinted at wanting to have a second baby with Travis. In February the make-up mogul made headlines after posting a picture of herself and Travis with "baby #2?" as the caption.